一个简单的Cache实现

2019独角兽企业重金招聘Python工程师标准>>>

import java.io.Serializable; import java.util.Date; import java.util.HashMap; import java.util.HashSet; import java.util.Iterator; import java.util.Map; import java.util.Set;

public class CacheManager {

        public static void main(String agrs[]) {
                    CacheConfiguration config = new CacheConfiguration();
                    config.setIsForever(false);
                    config.setBeginTime(new Date().getTime());
                    config.setDurableTime(1);

                    CacheManager cacheManager = CacheManager.getInstance();
                    String value = "this a cache ...";
                    String key = "cache";

                    cacheManager.add(key, value, config);

                    String results = (String) cacheManager.get(key);
                    System.out.println(results);
                    try {
                                Thread.sleep(1000 * 60 + 1000);
                    } catch (InterruptedException ex) {
                                ex.printStackTrace();
                    }
                    String results1 = (String) cacheManager.get(key);
                    System.out.println(results1);

        }
        private static Map cacheMap = new HashMap();
        private static Map cacheConfigMap = new HashMap();
        private static CacheManager cacheManager = null;

        private CacheManager() {
        }

        public static CacheManager getInstance() {
                    if (cacheManager == null) {
                                cacheManager = new CacheManager();
                                //at the same time ,it should start up the monit thread
                                ClearThread thread = new ClearThread();
                                thread.start();
                    }
                    return cacheManager;
        }

        public Object get(Object key) {
                    return cacheMap.get(key);
        }

        public boolean add(Object key, Object value, CacheConfiguration config) {
                    cacheMap.put(key, value);
                    cacheConfigMap.put(key, config);
                    return true;
        }

        public boolean remove(Object key) {
                    cacheMap.remove(key);
                    cacheConfigMap.remove(key);
                    return true;
        }

        private static class ClearThread extends Thread {

                    public void run() {
                                while (true) {
                                            Set tempSet = new HashSet();  //保存待删除的key
                                            Set configSet = cacheConfigMap.keySet();
                                            Iterator it = configSet.iterator();
                                            while (it.hasNext()) {
                                                        Object key = it.next();
                                                        CacheConfiguration configs = (CacheConfiguration) cacheConfigMap.get(key);
                                                        if (!configs.isIsForever()) {
                                                                    if ((new Date().getTime() - configs.getBeginTime()) >= configs.getDurableTime() * 60 * 1000) {
                                                                                tempSet.add(key);
                                                                    }
                                                        }
                                            }
                                            Iterator tempIt = tempSet.iterator();
                                            while (tempIt.hasNext()) {
                                                        Object key = tempIt.next();
                                                        cacheMap.remove(key);
                                                        cacheConfigMap.remove(key);
                                            }
                                            try {
                                                        Thread.sleep(1000 * 60L);
                                            } catch (InterruptedException ex) {
                                                        ex.printStackTrace();
                                            }
                                }
                    }
        }

}

class CacheConfiguration implements Serializable {

        private long beginTime;
        private boolean isForever = false;
        private int durableTime;

        public CacheConfiguration() {
                    // read cache property from configure file
        }

        public long getBeginTime() {
                    return beginTime;
        }

        public void setBeginTime(long beginTime) {
                    this.beginTime = beginTime;
        }

        public boolean isIsForever() {
                    return isForever;
        }

        public void setIsForever(boolean isForever) {
                    this.isForever = isForever;
        }

        public int getDurableTime() {
                    return durableTime;
        }

        public void setDurableTime(int durableTime) {
                    this.durableTime = durableTime;
        }

}

转载于:https://my.oschina.net/kingwjb/blog/261871